1. Field of the Invention
The present invention relates to a lens barrel which retracts lens groups in one mode, and which extends the lens groups to their predetermined positions in another mode for use. Particularly, the present invention relates to a lens barrel, a camera, a portable information terminal device and an image input apparatus which are suitable for a zoom lens capable of changing its focal length by moving multiple lens groups relative to one another.
2. Description of the Related Art
Photographic apparatuses, such as digital cameras, have undergone evolutions such as enhancement of the performance of photographic lenses including a zoom lens, and reduction in size in response to users' demand. Accordingly, there have been demands for the photographic apparatuses including a camera lens of a type in which a movable cylinder is placed in the camera main body except during photographing.
To meet a demand for making the camera main bodies (the photographic apparatuses) thinner, it is considered important to minimize to the maximum extent practicable the dimension in a photographic optical axis direction of a movable cylinder portion stored in the camera main body.
Against the background of such demands for making the camera main bodies thinner, there are disclosed techniques for retracting at least one of the lens groups from the photographic optical axis when the movable cylinder is collapsed into the camera main body for storage (see Japanese Patent No. 4373716 and Japanese Patent Application Publication No. 2005-266345, for example).
Each of these techniques causes one of the lens groups to retract from the photographic optical axis when the movable cylinder is stored in the camera main body (photographic apparatus). For this reason, each technique makes it possible to reduce the dimension of the movable cylinder in the photographic optical axis direction, and to make the camera main body (photographic apparatus) thinner.
However, in the techniques disclosed in Japanese Patent No. 4373716 and Japanese Patent Application Publication No. 2005-266345, when a lens group as the retractable lens is inserted to a position on the photographic optical axis, the lens group is positioned to the position on the photographic optical axis with a retaining frame for retaining the retractable lens engaged with a positioning member while abutting thereon and thereby kept from moving. Thus, there is a drawback that a collision sound may occur due to the abutment.